There are many applications in medical practice where a conical connector or adapter having a 6% taper (Luer type) is employed. These include coupling of tubing from intravenous fluid to the needle inserted in the vein of the patient, as well as the fitting of an hypodermic needle onto the pointed nozzle of a syringe.
The Luer type adapter is a cone shaped element of a standard taper angle, generally including a raised shoulder partway along its length. The overall length of the conical connector is 7.5 mm minimum. The complete connector includes two portions, one male and one female, frictionally coupled to one another. In practice, it is very difficult to grasp the two portions of the connector and disconect one from the other since the 6% taper angle permits a strong connection between the two. It is particularly difficult when one of the portions defines the base of an hypodermic needle in the vein of a patient from which the connector and attached tubing must be removed, for example, when introducing new infusion material. A similar difficulty is often encountered when removing an hypodermic needle from the nozzle of a syringe.
At present, there are known two methods of coupling and separating conical connectors of the Luer type from a needle. The first is a friction coupling described above wherein the outer surface of the male portion of the conical connector or of the syringe nozzle frictionally engages the inner surface of the base of the needle. Disengagement is accomplished manually by pulling one part from the other.
There is also known a device known as a Luer Lock which includes a threaded coupling which is screwed on and off the needle by rotation and to which the Luer type connector can be coupled. This device can be inconvenient in use since it requires twisting of the fluid tubing with the Luer Lock when being removed from the needle.